Water chiller

ABSTRACT

A water chiller includes at least one refrigeration apparatus, a water circuit in which circulates a water flow to be cooled down, and at least one fan generating an air flow (Fl) that is aspired from the outside. The refrigeration apparatus comprises a refrigerant circuit functioning in closed loop and comprising a compressor, at least one condenser, an expansion valve and an evaporator. The condenser is configured to release heat from the refrigerant to the air flow (Fl) under action of said at least one fan, the evaporator is configured to draw heat from the water flow to cool down said water flow. The water chiller further comprises at least one free cooling heat exchanger, configured to be exposed to the air flow (Fl), and connectable to the water circuit.

FOREIGN PRIORITY

This application claims priority to European Patent Application No.19180696.7 filed Jun. 17, 2019, and all the benefits accruing therefromunder 35 U.S.C. § 119, the contents of which in its entirety are hereinincorporated by reference.

BACKGROUND

The present invention concerns a water chiller.

Water chillers are used in buildings to cool water fed to air handlingunits installed in various rooms in which fresh air is blown. In largerooms, for example conference rooms or data centers, fresh air is alwaysneeded, thus cooling water may be necessary even if the outsidetemperature is lower than the temperature of the water.

In some places where the outside temperature is usually low, freecooling, which consists in directly refreshing water by heat exchangewith the outside air, is used as it has a good efficiency and has a lowenergy cost. Free cooling is therefore largely used in conference roomsor data centers.

The water chillers may also comprise a refrigeration apparatus includinga refrigerant thermodynamic circuit, to operate mechanical cooling. Inplaces where free cooling is possible in some periods, while mechanicalcooling remains necessary in summer periods due to high temperatures,water chillers able to operate in both modes may be desired. However, inmost cases, the buildings simply have two different water chillers foreach mode, generating a high cost and high volume and large footprint.

Some water chillers have a water circuit in parallel to the refrigerantcircuit, and have the condensers of the refrigeration apparatus inseries with free cooling heat exchangers, with respect to the air flow,to be able to selectively operate both modes within a same system.However, placing the condensers of the refrigeration apparatus in serieswith the free cooling heat exchangers means that the air flow has tocirculate successively through two exchangers. This doubles the pressuredrop generated during the passage of air through these heat exchangers,inducing a high power consumption on the fans of such water chillers.Such water chillers have therefore a lower efficiency compared tochiller without free cooling coils installed in series with condensers.

SUMMARY

An aim of the invention is to provide a new water chiller, which betteradapts to the various temperature conditions of the place where it isinstalled, to perform water cooling at a lower cost.

To this end, the invention concerns a water chiller comprising: at leastone refrigeration apparatus, a water circuit in which circulates a waterflow to be cooled down, at least one fan generating an air flow that isaspired from the outside; the refrigeration apparatus comprising arefrigerant circuit functioning in closed loop, the refrigerant circuitcomprising a compressor, at least one condenser, an expansion valve andan evaporator, said condenser being configured to release heat from therefrigerant to the air flow under action of said at least one fan, saidevaporator being configured to draw heat from the water flow to cooldown said water flow, whereas the water chiller further comprises atleast one free cooling heat exchanger, configured to be exposed to theair flow, and connectable to the water circuit, and whereas the waterchiller comprises controllable air flow direction means adapted toselectively: direct the air flow away from said at least one freecooling heat exchanger, in a mechanical cooling configuration in whichthe refrigeration apparatus is running and said at least one freecooling heat exchanger is disconnected from the water circuit; or directthe air flow through said at least one free cooling heat exchanger, in afree cooling configuration in which the refrigeration apparatus isstopped and said at least one free cooling heat exchanger is connectedto the water circuit.

Thanks to the invention, with the same apparatus, free cooling andmechanical cooling can be performed depending on the outside airtemperature conditions, allowing better performance, while the energycost remains low and without having to use two different apparatuses.

According to further aspects of the invention that are advantageous butnot compulsory, such a water chiller may incorporate one or several ofthe following features: The water chiller comprises a temperature sensorconfigured to measure an ambient air temperature outside the waterchiller, and a control unit configured to respectively run the waterchiller in mechanical cooling configuration or in free coolingconfiguration depending on the ambient air temperature beingrespectively superior or inferior to a temperature threshold. Thecontrol unit is configured to control the controllable closure means,the refrigeration system, and valves connecting the at least one freecooling heat exchanger to the water circuit. The controllable air flowdirection means are formed by louvers, that are movable between a closedposition, in which they form a panel preventing the air flow frompassing through them and directing the air flow towards the at least onefree cooling heat exchanger, and an open position, in which the air flowpasses through the louvers away from said at least one free cooling heatexchanger. The at least one condenser is provided on a vertical lateralside of the water chiller, and the at least one free cooling heatexchanger is provided on the same vertical side of the water chillerabove said at least one condenser. The at least one free cooling heatexchanger extends in vertical alignment with the at least one condenser.The at least one free cooling heat exchanger has a V shape protrudingfrom a vertical alignment of the at least one condenser. The at leastone free cooling heat exchanger and the controllable closing means areprovided on a top side of the water chiller above the at least one fan.The at least one free cooling heat exchanger and the controllableclosing means are provided as an additional module to be mounted on topof an existing water chiller. The water chiller comprises two symmetricsubassemblies, each subassembly comprising at least one condenser, atleast one free cooling heat exchanger, at least one fan and a set ofcontrollable air flow direction means, said two symmetric subassembliesbeing provided on both sides of a central plane and symmetric withrespect to said central plane.

DRAWING DESCRIPTION

Exemplary embodiments according to the invention and including furtheradvantageous features of the invention are explained below, referring tothe attached drawings, in which:

FIG. 1 is a synoptic drawing showing a water chiller according to afirst embodiment of the invention, running in a mechanical coolingconfiguration;

FIG. 2 is a synoptic drawing of the water chiller of FIG. 1, running ina free cooling configuration;

FIG. 3 is a synoptic drawing showing a water chiller according to asecond embodiment of the invention, running in a mechanical coolingconfiguration;

FIG. 4 is a synoptic drawing of the water chiller of FIG. 3, running ina free cooling configuration.

DETAILED DESCRIPTION

FIG. 1 represents a water chiller 2. The water chiller 2 is installed ona horizontal floor 6. A floor width W of the water chiller 2 denotes thehorizontal space, or footprint, occupied by the water chiller 2 on thefloor 6. The water chiller 2 may comprise a frame 4 that lies on thefloor 6. Axis X denotes a vertical direction.

The aim of the water chiller 2 is to cool down water for feeding anon-shown air handling unit which blows cold air into a room of abuilding, for example a workspace, a conference room, a datacenter,amongst others. The water chiller 2 therefore comprises a refrigerationapparatus 8, and a water circuit 10 in which circulates a water flow 100to be cooled down for feeding said non-shown air handling unit.Circulation of water in the water circuit 10 is run by a pump 102. Thepump 102 may be located outside the water chiller 2, as shown on FIG. 1,or inside the water chiller 2, as shown on FIG. 2.

According to a variant, the water chiller 2 may comprise more than onerefrigeration apparatus 8.

The water chiller 2 also comprise at least one fan 12 which forces thecirculation of an ambient air flow Fl from outside the water chiller 2inside the water chiller 2, through the frame 4. In one embodiment, thewater chiller 2 may comprise two fans 12. The air flow Fl generated bythe fans 12 has a generally vertical direction along axis X. The role ofthe fans 12 is disclosed below with more precision.

The refrigeration apparatus 8 comprises a refrigerant circuit 80functioning in closed loop, and comprising a compressor 82, at least onecondenser 84, an expansion valve 86 and an evaporator 88. The directionof circulation of the refrigerant in the refrigerant circuit 80 isindicated by arrows. The refrigerant circulates successively in thesefour components according to a thermodynamic cycle, which is brieflydescribed here below, in a steady state, during a high load operation ofthe refrigeration apparatus 8.

In the compressor 82, the refrigerant is in a gaseous state, and iscompressed from a low pressure to a high pressure, which raises thetemperature of the refrigerant from a low temperature to a hightemperature.

In the condenser 84, the refrigerant is in a bi-phasic state, includinggaseous and liquid refrigerant, and is condensed to a liquid state bythe condenser 84, by thermal exchange with the air flow Fl, which isforced by the fans 12 across the condenser 84. The refrigerant being ata high temperature, superior to an temperature T of the ambient airsurrounding the water chiller 2, the refrigerant releases heat to theair flow Fl under action of the fans 12.

In the expansion valve 86, the refrigerant is brought to the lowpressure, which lowers the temperature of the refrigerant to the lowtemperature while evaporating the refrigerant to the bi-phasic state.

In the evaporator 88, the refrigerant is in a bi-phasic state, includinggaseous and liquid refrigerant, and is evaporated to a gaseous state bythermal exchange with the water flow 100, which circulates within theevaporator 88. The refrigerant entering the evaporator 88 being at a lowtemperature, draws heat from the water flow 100 to be cooled down, whichis at a higher temperature than the refrigerant. The water flow 100exits the evaporator 88 at a temperature lower than before entering theevaporator 88.

In an embodiment, the water chiller 2 comprises several condensers 84.At least one of the condensers 84 may be vertical and mounted along alateral side of the water chiller 2, for example vertical sides 42 and44 of the water chiller 2.

The water chiller 2 may also comprise, in addition or in alternative tothe vertical condensers 84, other condensers 84 mounted closer to aninner side of the water chiller 2. These inner condensers 84 may have aninclined shape.

The water chiller 2 further comprises at least one free cooling heatexchanger 14, which is an air-water exchanger, also called hydroniccoil, or dry cooler. The heat exchanger 14 is connected to the watercircuit 10, and configured to be exposed to the air flow Fl, so as toperform free cooling. Free cooling consists in cooling down the waterflow 100 by direct heat exchange between the water and the air flow Fl,without having to rely on the refrigerant apparatus 8, in which therefrigerant must be first cooled down by the outside air before thewater can be cooled.

The free cooling heat exchanger 14 comprises non-shown apertures throughwhich the air flow Fl passes to the outside of the water chiller 2. Thefree cooling heat exchanger 14 extends along a vertical direction. Forexample, the water chiller 2 may comprise two free cooling heatexchangers 14 provided on two opposed sides of the water chiller 2.

The water chiller 2 further comprises controllable air flow directionmeans, adapted to selectively: direct the air flow Fl towards theoutside of the water chiller 2, and away from the free cooling heatexchangers 14, in a mechanical cooling configuration in which therefrigeration apparatus 8 is running and the free cooling heatexchangers 14 are disconnected from the water circuit 10; or direct theair flow Fl towards the free cooling heat exchangers 14, in a freecooling configuration in which the refrigeration apparatus 8 is stoppedand the free cooling heat exchangers 14 are connected to the watercircuit 10.

The controllable air flow direction means may be formed by louvers 16,that are movable between a closed position, shown on FIG. 2, in whichthey form a panel that prevents the air flow Fl from passing verticallyalong axis X through the louvers 16 and directs the air flow Fl,laterally from the axis X towards the free cooling heat exchanger 14,and an open position, shown on FIG. 1, in which the air flow Fl passesvertically along the axis X through the louvers 16 towards the outsideof the water chiller 2.

The water chiller 2 may comprise a temperature sensor 18 configured tomeasure the air ambient temperature T, and a control unit 20 configuredto run the water chiller 2 in respectively mechanical coolingconfiguration or in free cooling configuration depending on the ambientair temperature T being respectively superior or inferior to atemperature threshold Tmax.

The operation of the water chiller 2 is now described. In some places,the annual weather conditions may induce that a significant number ofdays see an average outside temperature T inferior to the temperaturethreshold Tmax, which can be 18° C. Under this temperature Tmax, freecooling is considered efficient and permits cooling down water with aquite high coefficient of performance (COP). Under such temperatureconditions, operating the water chiller 2 in mechanical cooling wouldconsume more energy, with a lower COP. It is therefore advantageous torun the water chiller 2 in free cooling configuration, by closing thelouvers 16. The closed louvers 16 form a panel facing the fans 12 rightin vertical direction. The air flow Fl is aspired by the fans 12 throughthe condensers 84 and the frame 4, then blown along axis X by the fans12. The air flow Fl is blocked by the closed louvers 16 and thereforeprevented from going vertically and forced through the free cooling heatexchangers 14 towards the lateral sides of the water chiller 2. Thewater circuit 10 is connected to the free cooling heat exchangers 14, sothat heat exchange is performed between the air flow Fl and the waterflow 100. During this free cooling configuration, the refrigerationapparatus 8 is stopped, for example by stopping the operation of thecompressor 82, to save energy. In free cooling configuration, the airflow Fl successively passes through the condensers 84 (upstream the fans12) then through the free cooling heat exchangers 14 (downstream thefans 12). The pressure drop and subsequent power consumption generatedby the air flow path are largely compensated by the high efficiency offree cooling and the stoppage of the compressor 82.

In case the ambient air temperature T is superior to the temperaturethreshold Tmax, the temperature difference between the temperature ofthe water flow 100 and the ambient air temperature T may not be largeenough to obtain an efficient free cooling. The water chiller 2 musttherefore operate in mechanical cooling configuration. The refrigerationapparatus 8 is started, for example by starting the compressor 82. Thelouvers 16 are opened, forming a large aperture right above the fans 12.The air flow Fl is aspired through the frame 4 and the condensers 84 andthen blow along axis X by the fans 12. The air flow Fl is able to flowthrough the free cooling heat exchangers 14 and through the openedlouvers 16. However, because the free cooling heat exchangers 14generate a pressure drop, the air flow Fl is therefore spontaneouslydriven vertically through the opened louvers 16, which generate a muchlower pressure drop. The air flow Fl therefore passes only through thecondensers 84, avoiding any unfavorable pressure drop that would occurin the prior-art air chillers where the condensers and free coolingexchangers are coupled. The air chiller 2 therefore benefits from thefull efficiency of mechanical cooling. The free cooling heat exchangers14 are disconnected from the water circuit 10, to further save energythat would be consumed by the pump 102 to circulate water towards,through and from the free cooling heat exchangers 14.

The control unit 20 is configured to control the louvers 16. The louvers16 may be driven between their closed and open position by a non-shownelectrical motor controlled by the control unit 20.

The control unit 20 controls the refrigeration system 8, for example bysending start or stop control signals to the compressor 82.

The water circuit 10 may comprise valves, for example three way valves,controlled by the control unit 20, for connecting or disconnecting thefree cooling heat exchangers 14 to the water circuit 10. The watercircuit 10 may comprise a valve 104 that directs the water flow 100towards the evaporator 88 in the mechanical cooling configuration onFIG. 1, or in the free cooling configuration on FIG. 2, directs thewater flow 100 towards the free cooling heat exchangers 14, via afeeding line 105. The water circuit 10 comprises a second valve 106,linked to the free cooling heat exchangers 14 by a return line 107. Thevalve 106 directs the water flow 100 towards the exterior of the waterchiller 2 on FIG. 1 and prevents the water flow 100 from going towardsthe return line 107. On FIG. 2, the valve 106 prevents the water flow100 from going towards the evaporator 88. The feeding line 105 and thereturn line 107 are not represented on FIG. 1 for the sake ofsimplification of the drawing. Except the condensers 84, the elements ofthe refrigeration apparatus 8 are not represented on FIG. 2 for the sakeof simplification of the drawing.

The louvers 16 are preferably provided on a top side 46 of the waterchiller 2 and above the fans 12.

The free cooling heat exchangers 14 may be provided on the same verticalside of the water chiller 2 as the vertical condensers 84 and abovethem. In an advantageous embodiment shown on FIGS. 1 and 2, the freecooling heat exchangers 14 may extend in vertical alignment with thevertical condensers 84. This allows keeping the width W of the waterchiller 2 unchanged. The footprint of the water chiller 2 is thereforenot increased by the fact that additional components for free coolingare added. Only the height of the water chiller 2 is increased.

The free cooling heat exchangers 14 and the louvers 16 may be providedas an additional module 22 to be mounted on top of an existing waterchiller. The free cooling heat exchangers 14 and the louvers 16 being ontop of the fans 12, which generally form the upper side of the standardwater chillers, they can be mounted in a pre-assembled module 22, thatcan be easily installed on an existing water chiller. To complete theinstallation of the pre-assembled module 22, an operator must thenprovide the necessary water connection lines 105 and 107 and theconnection of the pre-assembled module 22 with the control unit 20,which may be provided as a complementary component of the pre-assembledmodule 22.

In this exemplary embodiment, the water chiller 2 comprises twosymmetric subassemblies 24. Each subassembly 24 comprises a verticalcondenser 84, an inclined condenser 84, one free cooling heat exchanger14, one fan 12, and one set of louvers 16. The subassemblies 24 areprovided on both sides of a central plane, extending along the axis X,of the water chiller 2 and symmetric with respect to said central plane.The central plane is contained in a central division wall 48 of thewater chiller 2. More generally, each subassembly 24 may comprise atleast one condenser 84, at least one free cooling heat exchanger 14, atleast one fan 12 and one set of controllable air flow direction means.

A second embodiment of the invention is represented on FIGS. 3 and 4. Inthis embodiment, elements similar to the first embodiment have the samereferences and work in the same way. Only the differences with respectto the first embodiment are detailed here after.

In the embodiment of FIGS. 3 and 4, the free cooling heat exchangers 14have a V shape protruding from the vertical alignment of the verticalcondensers 84, instead of being in the vertical alignment of thevertical condensers 84. In such a case, the width of the additionalpre-assembled module 22 is increased, however the floor width W is notincreased, and this V-shape allows reducing the overall height of thewater chiller 2.

The V-shaped heat exchangers 14 may be provided as two heat exchangers140 angled with respect to each other.

The technical features of embodiments and variants disclosed here abovemay be combined to form new embodiments of the invention.

What is claimed is:
 1. A water chiller comprising: at least onerefrigeration apparatus, a water circuit in which circulates a waterflow to be cooled down, at least one fan generating an air flow that isaspired from the outside; the refrigeration apparatus comprising arefrigerant circuit functioning in closed loop, the refrigerant circuitcomprising a compressor, at least one condenser, an expansion valve andan evaporator, said condenser being configured to release heat from therefrigerant to the air flow under action of said at least one fan, saidevaporator being configured to draw heat from the water flow to cooldown said water flow, wherein the water chiller further comprises atleast one free cooling heat exchanger, configured to be exposed to theair flow, and connectable to the water circuit, and wherein the waterchiller comprises controllable air flow direction means adapted toselectively: direct the air flow away from said at least one freecooling heat exchanger, in a mechanical cooling configuration in whichthe refrigeration apparatus is running and said at least one freecooling heat exchanger is disconnected from the water circuit; or directthe air flow through said at least one free cooling heat exchanger, in afree cooling configuration in which the refrigeration apparatus isstopped and said at least one free cooling heat exchanger is connectedto the water circuit.
 2. A water chiller according to claim 1, whereinit comprises a temperature sensor configured to measure an ambient airtemperature outside the water chiller, and a control unit configured torespectively run the water chiller in mechanical cooling configurationor in free cooling configuration depending on the ambient airtemperature being respectively superior or inferior to a temperaturethreshold.
 3. A water chiller according to claim 2, wherein the controlunit is configured to control the controllable closure means, therefrigeration system, and valves connecting the at least one freecooling heat exchanger to the water circuit.
 4. A water chilleraccording to claim 1, wherein the controllable air flow direction meansare formed by louvers, that are movable between a closed position, inwhich they form a panel preventing the air flow from passing throughthem and directing the air flow towards the at least one free coolingheat exchanger, and an open position, in which the air flow passesthrough the louvers away from said at least one free cooling heatexchanger.
 5. A water chiller according to claim 1, wherein the at leastone condenser is provided on a vertical lateral side of the waterchiller, and wherein the at least one free cooling heat exchanger isprovided on the same vertical side of the water chiller above said atleast one condenser.
 6. Water chiller according to claim 5, wherein theat least one free cooling heat exchanger extends in vertical alignmentwith the at least one con
 7. Water chiller according to claim 5, whereinthe at least one free cooling heat exchanger has a V shape protrudingfrom a vertical alignment of the at least one condenser.
 8. Waterchiller according to claim 1, wherein the at least one free cooling heatexchanger and the controllable closing means are provided on a top sideof the water chiller above the at least one fan.
 9. Water chilleraccording to claim 8, wherein the at least one free cooling heatexchanger and the controllable closing means are provided as anadditional module to be mounted on top of an existing water chiller. 10.Water chiller according to claim 1, wherein it comprises two symmetricsubassemblies, each subassembly comprising at least one condenser, atleast one free cooling heat exchanger, at least one fan and a set ofcontrollable air flow direction means, said two symmetric subassembliesbeing provided on both sides of a central plane and symmetric withrespect to said central plane.